Chapter 12: Use of Single-cell Gel Electrophoresis Assays in Dietary Intervention Trials

The single-cell gel electrophoresis (SCGE) technique has been frequently used to investigate the impact of consumption of complex foods and individual constituents on DNA stability in humans. Since no division or cultivation of the indicator cells (in most studies lymphocytes) is required, this approach is less costly and time consuming than cytogenetic methods. Apart from single- and double-stand breaks and apurinic sites, which can be detected under standard conditions, it is also possible to assess the formation of oxidized DNA bases and alterations of DNA repair as well as protection of the DNA against chemical carcinogens. In total, 93 studies have been published since the first use of the Comet assay in this field in 1997. The results which emerged from these studies show that human foods contain specific highly protective components (e.g. gallic acid, xanthohumol, isoflavones); promising results were also obtained with beverages (coffee and other drinks), while mixed diets with vegetables and fruits conferred no or moderate protection; however, individual plant foods (e.g. kiwis and specific cruciferous vegetables) were highly protective. It is notable that prevention of DNA damage was rarely detected under standard conditions while evidence for reduced formation of oxidized DNA bases was found in approximately 30% of the trials. In some investigations it was possible to identify the modes of action by which specific compounds prevented damage of the genetic material in additional mechanistic experiments. The currently available data show that SCGE assays are a valuable tool for identifying dietary factors which improve the stability of the genetic material and prevent adverse health effects which are causally related to DNA damage.